Proteases are involved in a wide variety of biological processes. Disruption of the balance between proteases and protease inhibitors is often associated with pathologic tissue destruction.
Various studies have focused on the role of proteases in tissue injury, and it is thought that the balance between proteinases and proteinase inhibitors is a major determinant in maintaining tissue integrity. Serine proteinases from inflammatory cells, including neutrophils, are implicated in various inflammatory disorders, such as pulmonary emphysema, arthritis, atopic dermatitis and psoriasis. These and other inflammatory conditions are often associated with dysregulated levels of cytokines.
Proteases also degrade the vascular basement membrane and participate in the remodeling of the extracellular matrix to facilitate cell migration and invasion to promote tumor angiogenesis. Proteases release angiogenic growth factors bound to the extracellular matrix and to generate chemotactically active fragments derived from extracellular matrix components, which in turn exert chemotactic and mitogenic, modulatory activates on endothelial cells, smooth muscle cells and fibroblasts to participate in angiogenic processes. The list of protein factors angiogenically active in vivo includes fibroblast growth factors, Angiogenin, Angiopoietin-1, EGF, HGF, NPY, VEGF, TNF-alpha, TGF-beta, PD-ECGF, PDGF, IGF, IL8, and Growth hormone. Risks associated with current cytokine blocking agents include serious infections, anaphylaxis, and lupus-like syndrome. In addition, there is observed loss of clinical benefit after the drugs are stopped, and a small proportion of patients develop antibodies to the biological agents, which is likely to limit their efficacy with repeated use.
Synthetic and natural protease inhibitors have been shown to inhibit tumor promotion in vivo and in vitro. Previous research investigations have indicated that certain protease inhibitors belonging to a family of structurally-related proteins classified as serine protease inhibitors or SERPINS, are known to inhibit several proteases including trypsin, cathepsin G, thrombin, tissue kallikrein, as well as neutrophil elastase. The SERPINS are extremely effective at preventing/suppressing carcinogen-induced transformation in vitro and carcinogenesis in animal model systems. Systemic delivery of purified protease inhibitors reduces joint inflammation and cartilage and bone destruction as well.
Topical administration of protease inhibitors finds use in such conditions as atopic dermatitis, a common form of inflammation of the skin, which may be localized to a few patches or involve large portions of the body. The depigmenting activity of protease inhibitors and their capability to prevent ultraviolet-induced pigmentation have been demonstrated both in vitro and in vivo. Paine et al., Journal of Investigative Dermatology 116:587-595 [2001]. Also, protease inhibitors have been found to help wound healing (http://www.sciencedaily.com/releases/2000/10/001002071718.htm). Secretory leukocyte protease inhibitor was demonstrated to reverse the tissue destruction and speed the wound healing process when applied topically. In addition, serine protease inhibitors can also help to reduce pain in lupus erythematosus patients (See U.S. Pat. No. 6,537,968).
Naturally occurring protease inhibitors can be found in a variety of foods such as cereal grains (oats, barley, and maize), Brussels sprouts, onion, beetroot, wheat, finger millet, and peanuts. One source of interest is the soybean. The average level in soybeans is around 1.4 percent and 0.6 percent for Kunitz and Bowman-Birk respectively, two of the most important protease inhibitors. These low levels make it impractical to isolate the natural protease inhibitor for clinical applications.
Thus, there is a need for a method to produce large quantities of protease inhibitors that have desired characteristics of protein therapeutics, and for compositions that effectively deliver the protease inhibitor in a usable form.
The compositions and methods according to the invention fulfill some of the above needs and in particular offer an advantage in providing protease inhibitors that specifically target the activity of cytokines involved in pathologic and non-pathologic processes.